E. coli DnaG RNA polymerase domainWIKIMEDIA, LMO402Long known for its role in transcribing the genome’s code into messenger RNAs that can be translated into proteins, the enzyme RNA polymerase may also survey the genome for damage. That’s according to a study led by investigators at the New York University Langone Medical Center, which was published last month (January 8) in Nature. Biochemist Evgeny Nudler and his colleagues have described one way in which bacterial cells rely on RNA polymerase to start repairing DNA damage, which, the authors added, hint at pervasive transcription—the surprising revelation of noncoding RNA molecules and an axis of debate in molecular biology.
As RNA polymerases glide along strands of DNA transcribing them into new RNA molecules, the enzymes can at times get stuck when they encounter damage in the genome, like a zipper caught on a faulty tooth. “RNA polymerase gets stuck all the time,” explained Nudler. “It’s very picky.” While minor damage can cause the enzyme to merely pause briefly, major damage can stop it cold, disrupting gene expression and DNA replication.
One way to get RNA polymerase going again involves a molecule known as UvrD helicase. Through a series of in vitro and in vivo experiments, Nudler’s team showed how this molecule pulls the transcription enzyme back from the damage site by unwinding DNA strands. “Eight or 10 nucleotides back is enough to expose the ...
